1. Field of the Invention
This invention relates to an apparatus for controlling or eradicating nematodes and other soil-borne pests such as pathogens, fungus, and weeds, living in agricultural soil. In one aspect, this invention relates to an apparatus for in situ heating of soil infested with nematodes, pathogens, fungus, weeds, and other soil-borne pests. In one aspect, this invention relates to an apparatus for controlling or eradicating nematodes and other soil-borne pests such as pathogens, fungus, and weeds, living in agricultural soil using steam. In another aspect, this invention relates to a mobile apparatus for controlling or eradicating nematodes and other soil-borne pests such as pathogens, fungus, and weeds, living in agricultural soil.
2. Description of Related Art
Nematodes and other soil-borne pests, such as pathogens, fungus, and weeds, living in agricultural soil interfere with commercial cultivation of strawberries, tomatoes, and other crops. Traditionally, these pests have been controlled using chemical poisons, for example, methyl bromide, which are undesirable from an environmental perspective. Methyl bromide is a particularly powerful ozone-depleting agent as result of which its use is being phased out. While other chemical means of pest control have been documented, it is known that heat may be used to control the nematodes and other pests. In particular, if the soil is heated to a temperature of about 180° F. and held there for approximately one hour, the nematodes and other pests are generally eradicated. It is not desirable to heat the soil to higher temperatures due to the adverse affect that such higher temperatures would have on the agricultural productivity of the soil.
A variety of devices designed to heat soil and eradicate pest species are known. These include buried pipes designed to deliver hot air or steam to the soil, rakes with attached blankets that can be dragged through the soil, injecting steam to the desired depth, vehicles that inject steam into the soil, and devices that lift the soil out of the field, heat-treat the soil in mixed beds or heated augers, and then deposit the soil back in the field. However, all of the presently available technologies suffer from drawbacks that have made them unattractive as a cost-effective means of soil treatment in the United States. Technologies involving steam injection generally suffer from relatively low thermal efficiency. The installation of fixed pipes to deliver steam or heated air is expensive and inconvenient, and such a system of pipes may require considerable maintenance. Vehicles that inject steam into the soil, or systems that lift and heat the soil, have been expensive to develop and operate and may operate at low thermal efficiencies.